My goal is to render two images: one for an object that I created in Blender which I understand how to do and the other image is for the shadow that the object casts.

The background on which the shadow is projected should be invisible, in fact these two images must be transparent and I understand how to do that with an object, but doing this for object's shadow is what I don't have a slightest idea about. The image of an object and its shadow will be then drawn in a separate program - think of a tile in a game with the shadow that object on that tile is casting on other tiles above, so at first a shadow will be drawn then an object itself.

A shadow must be transparent, i.e. it should have a transparent background and ideally it should have an alpha channel reflecting the strength of the light source.

I found one similar question that refers to shadow catcher, but I'm still not sure how to separate shadow rendering from the object rendering so that I could get a separate render of a shadow: 2.81 Transparent Background Shadow Catcher

  • $\begingroup$ I've been waiting for some magical Node to be suggested, but as you've mentioned this is for an external application, the end result would be unclear. You might like to take a look at a rather basic but effective form of shadowing. It bypasses the inbuilt shadowing system altogether and does produce separately rendered shadows planes - blender.stackexchange.com/questions/518/… $\endgroup$
    – Edgel3D
    Aug 9, 2022 at 23:14
  • $\begingroup$ Thank you, I'll experiment with this. $\endgroup$
    – J. A.
    Aug 10, 2022 at 6:27
  • $\begingroup$ I think the best bet would be to use shadow catcher plane with Cycles, this could render an object and a shadow on a transparent background. When I need to render a shadow I probably can use a pink texture + unshaded material on the whole object then cut it via Gimp or the like from the resultant image. That seems like a lot of pain, but I can see it could work out. If I'm successful I'll post an update with what I end up having. $\endgroup$
    – J. A.
    Aug 10, 2022 at 7:54


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